I think if Facebook provides a marketplace on their own platform and uses Facebook coins as a payment method, then people who use the platform will buy. because the facebook platform is quite large and has many users, so they will only get the attention of their users. because for crypto users in general, stable coins are less promising and large profit potential from stable investments is very small.
Actually it depends on Facebook user because some of the person doesn't really trust some Facebook process by other project. By the scammer spread on Facebook, it become more hard to trust using Facebook and I also think that it would not be healthy if we use Facebook coin and I don't believe on that.